Testguard circuit with auto monitoring and end-of-life circuitry

ABSTRACT

A manually switched Testguard circuit with auto-monitoring and end-of-life circuitry is provided. The manually switched Testguard circuit interrupts the flow of current through a pair of lines, wherein one of the pair of lines extends between a line input and a line output and the other line extends between a neutral input and a neutral output. The manually switched Testguard circuit includes a monitoring module for detecting an end-of-life condition. The monitoring module includes a simulated ground fault generator for simulating a ground fault; an auto-monitoring logic module; a relay synchronized switch; and an end-of-life switch for disabling the manually switched Testguard circuit if certain Testguard component failures are detected.

1. FIELD OF USE

The present invention relates generally to electrical safety devices andmore particularly to a manual reset Testguard circuit with automonitoring and end-of-life circuitry.

2. DESCRIPTION OF PRIOR ART (BACKGROUND)

Conventional electrical appliances typically receive alternating current(AC) power from a power supply, such as an electrical outlet, through apair of conducting lines. The pair of conducting lines, often referredto as the line and neutral conductors, enable the electrical appliance,or load, to receive the current necessary to operate.

The connection of an electrical appliance to a power supply by a pair ofconducting lines creates a number of potentially dangerous conditions.In particular, there exists the risk of ground fault, leakage currentsand grounded neutral conditions in the conducting lines. When a groundfault or leakage current condition occurs it creates an imbalancebetween the currents flowing in the line and neutral conductors. Agrounded neutral condition occurs when the neutral conductor is groundedat the load. A ground fault condition is extremely dangerous and canresult in serious injury.

Ground fault and leakage current interrupters include circuit breakers,receptacles, portable and cord mounted protection devices. They may betroubled by false tripping, even though they pass all present industrystandards. One cause of false tripping is disconnection of the power toinductive appliances, particularly by unplugging the appliances.

Examples of these appliances include electric shavers, high intensitylamps, and small cooling fans, such as are used for cooling electronicequipment. Unplugging these appliances generates an arc between the plugand the receptacle, resulting in the superimposition of several volts ofwide band noise onto the power line. Due to the wide band nature of thenoise, even a very small stray coupling capacitance will couple thenoise from the power line conductor into the ground fault circuit,causing a false trip.

Grounded neutral detection is provided by a dormant oscillator circuitconfiguration. The detector circuit includes first and second sensorcoils through which the line and neutral conductors of the protectedcircuit pass. If a load side grounded neutral condition occurs, bothcores sensor coils are coupled together to create an oscillating signalthat is applied through a coupling capacitor to the above-describedoperational amplifier followed by a window comparator, this actiongenerates a trip signal.

It has been found that wide band noise induced by load related switchingphenomena such as is caused by unplugging inductive appliances causesfalse tripping of the ground fault interrupter.

Ground fault circuit and leakage current interrupters are well known inthe art and are commonly used to protect against ground fault, leakagecurrents and grounded neutral conditions. In general, GFCI devices sensethe presence of ground fault and grounded neutral conditions in theconducting lines and in response thereto, open at least one of theconducting lines between the power supply and the load to eliminate thedangerous condition.

In U.S. Pat. No. 5,177,657, to M. Baer et al, there is disclosed aground fault interrupter circuit which interrupts the flow of current toa pair of lines extending between a source of power and a load. Theground fault interrupter circuit includes a circuit breaker comprising anormally open switch located in one or both of the lines, a relaycircuit for selectively closing the normally open switch, an electroniclatch circuit operable in first and second bi-stable states and a faultsensing circuit for sensing the presence of a fault condition in atleast one of the lines. The electronic latch circuit causes the relaycircuit to close the normally open switch and maintain the normally openswitch in its closed position when the electronic latch circuit is inthe first bi-stable state. The electronic latch circuit also causes therelay circuit to permit the normally open switch to return to itsnormally open condition when the latch circuit is in its secondbi-stable state. A fault sensing circuit senses the presence of a faultcondition in at least one of the lines and causes the electronic latchto latch in its second state upon detection of the fault condition.

In U.S. Pat. No. 5,418,678 to T. M. McDonald, there is disclosed animproved ground fault circuit interrupter (GFCI) device which requiresmanual setting following initial connection to an AC power source ortermination of a power source interruption. The improved GFCI deviceutilizes a controlled switching device which is responsive to a loadpower signal for allowing the relay contact sets of the GFCI device tobe closed only when power is being made available at the output or loadterminals. The controlled switching device preferably comprises anopto-isolator or other type of switching device which provides isolationbetween the GFCI input and output terminals when the relay contact setsare open. The improved GFCI device may be incorporated into portableunits, such as plug-in or line cord units, for use with unprotected ACreceptacles.

In U.S. Pat. No. 4,816,957 to L. F. Irwin there is disclosed an adapterunit comprising a moisture resistant housing within which is carried animproved, self-testing ground line fault interrupter device. Theimproved device is electrically interconnected with a connector carriedexternally of the adapter housing so that the unit can be pluggeddirectly into a standard duplex outlet of an existing circuit. Theapparatus includes circuitry that automatically tests the operability ofthe device when it is plugged into a duplex outlet without the need formanual manipulation of test buttons or other overt action by the user.

In U.S. Pat. No. 4,578,732 to C. W. Draper et al there is disclosed awall socket type ground fault circuit interrupter having a pair ofsockets, a reset button and a test button that are accessible from thefront of the interrupter. The interrupter has latched snap-actingcontacts and a novel latching relay structure for maintaining thesnap-acting contacts in a circuit making position. The snap-actingcontacts permit all of the components including the monitoring toroids(sensing transformers) and the power supply to be respectively locatedand connected at the load side of the snap-acting contacts so that allof the circuits of the interrupter are de-energized when the contactssnap to a circuit opening position. The snap-acting contact mechanismand relay are provided with structures which provide the interrupterwith a trip-free mode of contact actuation and accordingly a tease-proofsnap-acting contact operation.

One drawback of GFCI devices of the type described above is that theGFCI device generally includes a large solenoid to selectively open andclose the switching device. Specifically, the solenoid generallyrequires a constant supply of line voltage (approximately 120 volts) inorder to switch and sustain the solenoid in its energized state. As aconsequence, the solenoid acts as a large power drain source.

UL943 now requires all GFCIs to indicate “end of life” if the devicefails to trip when the test button is manually operated. However, evenif end-users regularly tested their devices, a GFCI device that did nottest properly could nevertheless be reset, and continue to providepower, without providing ground-fault protection. Without a built-inpower denial feature, a consumer could erroneously and tragically assumethat if power is available, so is protection. Many end users were (andcontinue to remain) unaware of the need for regular testing, despitemanufacturers' warnings; and others, who were aware, were not alwaysconscientious in performing the testing. The latest edition of UL943 hasintroduced requirements for all GFCI's to include “auto monitoring” (AM)and “end of life” (EOL), whereby the GFCI will test itself at regularintervals (AM), in the case of a GFCI circuit failure provide a userindication and remove itself from service (EOL).

Auto monitoring (AM), end-of-life (EOL) typical events are the groundfault sensing components (toroids and integrated circuit) are open orshort circuited; the trip solenoid and/or its control circuit is faulty,or the switching semiconductor (SCR) controlling the trip solenoidcontrol circuit is open or short circuited.

Thus, there is a need for a solenoid of sufficient rating for use in aline voltage GFCI device but with reduced tendency to fail due to highvoltages and currents associated with typical line voltages. There isalso a need for a ground fault interrupter which does not generate afalse trip in response to wide band noise in the protected circuit.There is also a need for such a ground fault circuit with improvedimmunity to wide band noise which also responds to sputtering arcfaults.

There is also a need for a manual reset Testguard circuit with manualand automatic testing of the often-failed components of a GFCI anddenial of power if testing fails.

SUMMARY OF THE INVENTION

A manually switched test guard circuit for interrupting the flow ofcurrent through a pair of power lines connected between a load and powersource is provided. The circuit includes a ground fault circuitinterrupter (GFCI) having a pair of ganged manually switched first andsecond switches disposed between the load and power source. Each of themanual switches comprises a connected position for connecting the loadand power source and a disconnected position for interrupting, ordisconnecting the load from the power source. A relay circuit having asolenoid controls the first and second manual switches. The test guardcircuit includes a fault detection circuit for detecting a ground faultin the pair of lines and a bi-stable electronic latch circuit fordeenergizing the relay circuit if a fault is detected. The test guardcircuit also includes a monitoring module integrated with the GFCI. Themonitoring module includes a simulated ground fault generator forgenerating a ground fault on-pulse for testing the fault detectioncircuit and the first bi-stable electronic latch circuit. The monitoringmodule also includes a relay synchronized switch for disabling currentto the relay circuit during the ground fault on-pulse; anauto-monitoring logic module for monitoring the first bi-stableelectronic latch circuit during the ground fault on-pulse; anend-of-life switch for deenergizing the relay circuit and switching eachof the manual switches to the disconnected position if theauto-monitoring logic module determines the first bi-stable electroniclatch circuit has failed. The test guard circuit also includes a powersupply circuit for providing current to the relay synchronized switch,and the relay synchronized switch provides current to the faultdetection circuit via the solenoid and wherein the current maintains themanually switched switches in the connected position if a ground faultis not detected. The solenoid includes a magnetic field when energizedby the current provided by the relay synchronized switch and acollapsing magnetic field when the current is interrupted by the relaysynchronized switch during the ground fault on-pulse. The collapsingmagnetic field provides current through the solenoid to maintain themanual switches in the connected position during the ground faulton-pulse. The collapsing magnetic field provides current to the GFCI ICduring the ground fault on-pulse.

The invention is also directed towards a method for intermittentlytesting components of a ground fault circuit interrupter (GFCI) forinterrupting power between a line input and a line output. The methodincludes providing a simulated ground fault generator for generating aground fault test on-pulse; providing a relay for disconnecting manualswitches for interrupting power between the line input and the lineoutput when the relay is deenergized. The method also includes providinga relay synchronized switch for interrupting current to the relay forthe duration of the ground fault test on-pulse. The method includesswitching on a bi-stable electronic latch circuit during the groundfault test on-pulse; and providing a monitoring circuit for detectingswitch-on failure of the bi-stable electronic latch circuit during theground fault test on-pulse. The method also includes maintaining therelay in an energized state and the manual switches in the connectedposition for the duration of the ground fault test on pulse.

Additional objects, as well as features and advantages, of the presentinvention will be set forth in part in the description which follows,and in part will be obvious from the description or may be learned bypractice of the invention. In the description, reference is made to theaccompanying drawings which form a part thereof and in which is shown byway of illustration specific embodiments for practicing the invention.These embodiments will be described in sufficient detail to enable thoseskilled in the art to practice the invention, and it is to be understoodthat other embodiments may be utilized and that structural changes maybe made without departing from the scope of the invention. The followingdetailed description is, therefore, not to be taken in a limiting sense,and the scope of the present invention is best defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are hereby incorporated into andconstitute a part of this specification, illustrate various embodimentsof the invention and, together with the description, serve to explainthe principles of the invention. In the drawings wherein like referencenumerals represent like parts:

FIG. 1 is a schematic circuit diagram of a manual reset ground faultcircuit interrupter (GFCI) with monitoring features of the presentinvention; and

FIG. 2 is a timing relationship diagram of the monitoring features shownin FIG. 1.

DETAILED DESCRIPTION

The following brief definition of terms shall apply throughout theapplication:

The term “comprising” means including but not limited to, and should beinterpreted in the manner it is typically used in the patent context;

The phrases “in one embodiment,” “according to one embodiment,” and thelike generally mean that the particular feature, structure, orcharacteristic following the phrase may be included in at least oneembodiment of the present invention, and may be included in more thanone embodiment of the present invention (importantly, such phrases donot necessarily refer to the same embodiment);

If the specification describes something as “exemplary” or an “example,”it should be understood that refers to a non-exclusive example; and

If the specification states a component or feature “may,” “can,”“could,” “should,” “preferably,” “possibly,” “typically,” “optionally,”“for example,” or “might” (or other such language) be included or have acharacteristic, that particular component or feature is not required tobe included or to have the characteristic.

Referring now to FIG. 1 and FIG. 2, there is shown a manual resetTestguard circuit including ground fault circuit interrupter(hereinafter GFCI) circuit constructed and operated according to theteachings of the present invention during the normal GFCI operationwindow shown in FIG. 2. The end of life (herein after monitoring) moduleis constructed and operated according to the teachings of the presentinvention during the Auto Monitoring EOL Window shown in FIG. 2.

As will be discussed in detail below, the GFCI automatically protects aload from ground fault conditions upon the initial connection of Input Lto Load L and Input N to Load N. Furthermore, once GFCI protects theload from a ground fault condition, GFCI 11 can be reset to protectagainst further ground fault conditions.

GFCI circuit shown in FIG. 1 includes components arranged as shown anddiscussed herein. The GFCI circuit includes ganged switches SW1 and SW2,a relay circuit 15, a power supply circuit 17, a fault detection circuit21 for detecting an electrical fault, a bi-stable electronic latchcircuit 23, and a test circuit 27. Also shown in FIG. 1 is a monitoringcircuit 101. The monitoring circuit includes a relay synchronized switch31, a simulated ground fault generator 33, an end of life logic circuit35, and End of Life Switch 35A.

Switches SW1 and SW2 are located in the line and neutral conductivelines, respectively, between a power source and a load. Switches SW1 andSW2 can be positioned in either of two connective positions. In thefirst connective position, which is illustrated in FIG. 1, switches SW1and SW2 are positioned such that the input power source is connected tothe load. In the second connective position, which is the oppositeposition illustrated in FIG. 1, switches SW1 and SW2 are positioned suchthat the input power source is disconnected from the load.

Relay circuit 15 acts to selectively position switches SW1 and SW2 ineither its first connective position or its second connective position.Relay circuit 15 comprises a solenoid K1.

Solenoid K1 is ganged to the circuit breaker contacts of switches SW1and SW2 and is responsible for selectively controlling the connectiveposition of switches SW1 and SW2. Before power is applied to GFCI 11,solenoid K1 15 position switches SW1 and Sw2 are in the oppositeconnective position as shown. When current I(K1) is supplied to solenoidK1 via power supply circuit 17 via Relay Synchronized Switch 31 there isinsufficient current to latch switches SW1 and SW2, thus requiringmanual latching. There is sufficient current I(k1) through solenoid K115 to maintain switches SW1 and SW2 in a latched connective position.

Power supply circuit 17 provides power for the GFCI circuit. Powersupply circuit 17 comprises rectifier diode D9, voltage droppingresistors R18, R21, R22, and R23, and capacitor C3. Also shown in FIG.1, is Varistor MOV1 which has a value of 150 volts and acts to protectagainst a voltage surge from the AC power source.

Fault detection circuit 21 detects both ground fault and groundedneutral conditions in the conductive lines when switches SW1 and SW2 arein their second connective position. Fault detection circuit 21comprises a sense transformer T1, a grounded neutral transformer T2, acoupling capacitor C8, a noise suppression capacitor C1, a feedbackresistor R3, and a ground fault interrupter integrated circuit GFCI IC.

Sense transformer T1 senses an electrical fault such as the currentdifferential between the line and neutral conductive lines and upon thepresence of a ground fault condition, transformer T1 induces anassociated output from its secondary windings. Grounded neutraltransformer T2 acts in conjunction with transformer T1 to sense thepresence of grounded neutral conditions and, in turn, induce anassociated output. Coupling capacitor C8 couples the AC signal from thesecondary winding of transformer T1 to GFCI IC. Capacitor C1 preventsfault detection circuit 21 from operating in response to linedisturbances such as electrical noise and lower level faults.

Together capacitor C8 and resistor R3 set the minimum fault current atwhich fault detection circuit 21 provides an output signal to latchcircuit 23. GFCI IC amplifies a fault signal generated by transformer T1and generates an output pulse on pin 5 to activate latch circuit 23.

Upon detection of a ground fault or grounded neutral condition GFCI ICgenerates an output pulse on pin 5 to activate latch circuit 23 (e.g.,Q2 turns “on” during the “off” period during normal GFCI operation shownin FIG. 2. Activated Latch Circuit 23 deactivates or de-energizessolenoid K1 15 via Relay Synchronized Switch 31 by removing energizingcurrent I(K1). Latch circuit 23 comprises NPN transistor Q2, and a noisesuppression capacitor C2. Noise suppression capacitor C2 preventstransistor Q2, when in its nonconductive state, from firing as a resultof electrical noise. It will be appreciated from FIG. 2 that if theTestguard Circuit 11 detects a ground fault or grounded neutralcondition during the auto monitoring window Q2 will not transition backto the off state, i.e., will stay on longer than the Auto monitoring EOLwindow, thus deenergizing K1 15

Test circuit 27 provides a means of testing whether the GFCI circuit isfunctioning properly. Test circuit 27 comprises a test switch ofconventional push-in type design. When the test switch is depressed toenergize test circuit 27, resistor R12 provides a simulated faultcurrent to transformer T1 which is similar to a ground fault condition.

Auto Monitoring and End of Life

The monitoring module 101 includes a relay synchronized switch 31, asimulated ground fault generator 33, an auto monitoring and end of lifecircuit 35, and End of Life Switch 35A.

Simulated ground fault generator (SGFG) 33 includes the logic and meansnecessary to simulate a periodic ground fault. See FIG. 2. During normalGFCI operation the SGFG 33 is off. During the auto monitoring windowSGFG generates a short on pulse setting the base timing of the automonitoring end of life (EOL) window. The SGFG pulse is sensed by GFCIcircuit 21 as a ground fault. Upon detection of the simulated groundfault GFCI IC generates an output pulse on pin 5 to activate latchcircuit 23 (Q2)

The SGFG pulse is also sensed by GFCI Relay Synchronized Switch 31 whichincludes the logic and means necessary to temporarily turn off thenormal GFCI fault detection described above when the SGFG 33 generatesthe short on pulse for the purpose of auto monitoring the ground faultdetection circuit. The tested GFCI components include the sensetransformer T1, the grounded transformer T2, the GFCI IC and thebi-stable electronic latch circuit 23. It will be appreciated thatcurrent I(K1) through solenoid K1 15 is the power source for GFCI IC inGFCI circuitry 21. It will be further appreciated that the timingwindow, or pulse period, set by SGFG is of short enough duration so whenK1 15 is temporarily turned off during the auto monitoring EOL windowthe collapsing K1 15 magnetic field maintains sufficient current flowthrough K1 15 to maintain switches SW1 and SW2 in their connectivepositions. It will be further appreciated that the collapsing K1 15magnetic field maintains sufficient power to the GFCI IC for theduration of the auto monitoring EOL window.

The auto-monitoring and EOL logic (monitoring) circuit 35 determines thenumber of times Q2 does not turn on during successive auto monitoringEOL windows. As shown in FIG. 2, if test question Q2 ON? is off then Q2has failed to turn on. If Q2 fails to turn on for a predetermined numberof times the GFCI fault detection circuitry is defective and the EOLswitch 35A is activated, thus deenergizing solenoid K1.

The versions of the present invention described above are intended to bemerely exemplary and those skilled in the art shall be able to makenumerous variations and modifications to it without departing from thespirit of the present invention. All such variations and modificationsare intended to be within the scope of the present invention as definedin the appended claims. For example, it should be noted that theparticular components which make up the aforementioned embodiments maybe interchanged or combined to form additional embodiments.

What is claimed is:
 1. A test guard circuit for interrupting a flow ofcurrent through a pair of lines, wherein one of the pair of linesextends between a line input and a line output and the other lineextends between a neutral input and a neutral output, the test guardcircuit comprising: a ground fault circuit interrupter (GFCI) whereinthe GFCI comprises: a first switch having a first input terminal and afirst contact terminal; a second switch having a second input terminaland a second contact terminal, wherein the first switch is ganged to thesecond switch; a relay circuit for controlling the first and secondswitches, wherein each of the switches comprises a first non-energizedposition and a second energized position and wherein the first switch isconnected between the line input and the line output and the secondswitch is connected between the neural input and the neutral output; afault detection circuit for detecting a ground fault in the pair oflines, and wherein the relay circuit comprises a solenoid; a firstbi-stable electronic latch circuit for deenergizing the relay circuitwhen a fault is detected; a monitoring module integrated with the GFCI,the monitoring module comprising: a simulated ground fault generator forgenerating a ground fault on pulse for testing the fault detectioncircuit and the first bi-stable electronic latch circuit; a relaysynchronized switch for disabling current to the relay circuit duringthe ground fault on pulse; an auto-monitoring logic module formonitoring the first bi-stable electronic latch circuit during theground fault on pulse; an end-of-life switch for disabling the relaycircuit if the auto-monitoring logic module determines the firstbi-stable electronic latch circuit has failed; and wherein the GFCIfurther comprises: a power supply circuit for providing current to therelay synchronized switch, and wherein the relay synchronized switchprovides current to the fault detection circuit via the solenoid.
 2. Thetest guard circuit as in claim 1 wherein the fault detection circuitcomprises: a sense transformer; a grounded neutral transformer; and aGFCI Integrated Circuit (IC) coupled to the sense transformer and thegrounded neutral transformer.
 3. The test guard circuit as in claim 2wherein the auto-monitoring logic module comprises a predeterminednumber of failures of the GFCI circuit in response to the simulatedground fault on pulse to test the GFCI circuit, wherein the tested GFCIcircuit comprises: the sense transformer; the grounded neutraltransformer; the GFCI Integrated Circuit (IC) coupled to the sensetransformer and the grounded neutral transformer; and the firstbi-stable electronic latch circuit.
 4. The test guard circuit as inclaim 1 wherein the first bi-stable electronic latch circuit comprisesan NPN transistor.
 5. The test guard circuit as in claim 1 wherein thesolenoid comprises a magnetic field when energized by the currentprovided by the relay synchronized switch and a collapsing magneticfield when the current is interrupted by the relay synchronized switchand wherein the collapsing magnetic field provides current through thesolenoid and the fault detection circuit during the ground fault onpulse.
 6. A ground fault circuit interrupter circuit for interrupting aflow of current through a pair of lines, wherein one of the pair oflines extends between a line input and a line output and the other lineextends between a neutral input and a neutral output, the GFCI circuitcomprising: a fault detection circuit for detecting a ground fault inthe pair of lines; a relay circuit comprising a solenoid for controllingthe first and second switches, wherein each of the switches comprises afirst non-energized position and a second energized position and whereinthe first switch is connected between the line input and the line outputand the second switch is connected between the neural input and theneutral output; a first bi-stable electronic latch circuit fordeenergizing the relay circuit when a fault is detected by the faultdetection circuit; a monitoring module integrated with the GFCI, themonitoring module comprising: a simulated ground fault generator forgenerating a ground fault on pulse for testing fault detection circuitcomponents; a relay synchronized switch for providing current to thefault detection circuit through the relay circuit, and wherein the relaysynchronized switch turns off the fault detection circuit byinterrupting current to the fault detection circuit and the relaycircuit; and wherein the relay circuit maintains the second energizedposition and provides operating current to the fault detection circuitfor the duration of the ground fault on pulse.
 7. The GFCI circuit as inclaim 6 further comprising: an auto-monitoring logic module formonitoring the first bi-stable electronic latch circuit during theground fault on pulse; an end-of-life switch for disabling the relaycircuit if the auto-monitoring logic module determines the firstbi-stable electronic latch circuit has failed; and a power supplycircuit for providing current to the relay synchronized switch.
 8. TheGFCI circuit as in claim 6 wherein the tested fault detection circuitcomponents comprise: a sense transformer; a grounded neutraltransformer; a GFCI Integrated Circuit (IC) coupled to the sensetransformer and the grounded neutral transformer; and the firstbi-stable electronic latch circuit.
 9. A method for intermittentlytesting components of a ground fault circuit interrupter (GFCI) forinterrupting power between a line input and a line output, the methodcomprising: providing a simulated ground fault generator for generatinga ground fault test on pulse; providing a relay for controlling switchesfor interrupting power between the line input and the line output whenthe relay is deenergized; providing a relay synchronized switch forinterrupting current to the relay for the duration of the ground faulttest on pulse; switching on a first bi-stable electronic latch circuitduring the ground fault test on pulse; providing a monitoring circuitfor detecting switch-on failure of the first bi-stable electronic latchcircuit during the ground fault test on pulse; and maintaining the relayin an energized state for the duration of the ground fault test onpulse.
 10. The method as in claim 9 further comprises providing anend-of-life switch for deenergizing the relay if the monitoring circuitdetermines the first bi-stable electronic latch circuit has failed. 11.A manually switched test guard circuit for interrupting a flow ofcurrent through a pair of lines, wherein one of the pair of linesextends between a line input and a line output and the other lineextends between a neutral input and a neutral output, the test guardcircuit comprising: a ground fault circuit interrupter (GFCI) whereinthe GFCI comprises: a manually switched first switch having a firstinput terminal and a first contact terminal; a manually switched secondswitch having a second input terminal and a second contact terminal,wherein the manually switched first switch is ganged to the manuallyswitched second switch; a relay circuit connected to the manuallyswitched first and second switches, wherein each of the manuallyswitched switches comprises a connected position and a disconnectedposition and wherein the manually switched first switch is connectedbetween the line input and the line output and the manually switchedsecond switch is connected between the neural input and the neutraloutput; a fault detection circuit for detecting a ground fault in thepair of lines, and wherein the relay circuit comprises a solenoid; afirst bi-stable electronic latch circuit for deenergizing the relaycircuit when a fault is detected; a monitoring module integrated withthe GFCI, the monitoring module comprising: a simulated ground faultgenerator for generating a ground fault on pulse for testing the faultdetection circuit and the first bi-stable electronic latch circuit; arelay synchronized switch for disabling current to the relay circuitduring the ground fault on pulse; an auto-monitoring logic module formonitoring the first bi-stable electronic latch circuit during theground fault on pulse; an end-of-life switch for disabling the relaycircuit if the auto-monitoring logic module determines the firstbi-stable electronic latch circuit has failed; wherein the GFCI furthercomprises: a power supply circuit for providing current to the relaysynchronized switch, and wherein the relay synchronized switch providescurrent to the fault detection circuit via the solenoid and wherein thecurrent maintains the manually switched switches in the connectedposition; and wherein the solenoid comprises a magnetic field whenenergized by the current provided by the relay synchronized switch and acollapsing magnetic field when the current is interrupted by the relaysynchronized switch and wherein the collapsing magnetic field providescurrent through the solenoid to maintain the manually switched switchesswitches in the connected position during the ground fault on pulse. 12.The manually switched test guard circuit as in claim 11 wherein thefault detection circuit comprises: a sense transformer; a groundedneutral transformer; and a GFCI Integrated Circuit (IC) coupled to thesense transformer and the grounded neutral transformer.
 13. The manuallyswitched test guard circuit as in claim 12 wherein the auto-monitoringlogic module comprises a predetermined number of failures of the GFCIcircuit in response to the simulated ground fault on pulse to test theGFCI circuit, wherein the tested GFCI circuit comprises: the sensetransformer; the grounded neutral transformer; the GFCI IntegratedCircuit (IC) coupled to the sense transformer and the grounded neutraltransformer; and the first bi-stable electronic latch circuit.